Two-piece distal catheter assembly

ABSTRACT

Distal catheter assemblies, catheters, and methods for minimizing damage to heat and/or magnetically sensitive components are provided. A distal catheter assembly comprises a distal housing having a cavity and a separate proximal mounting member. A first component, e.g., a sensor, is mounted within the cavity of the housing, and a second component, e.g., a steering assembly or RF wire, is mounted to the proximal mounting member. If the proximal mounting member is hollow, it may have a window to provide access to the inner surface of the proximal mounting member to facilitate mounting of the second component. After the first and second components are mounted, the proximal mounting member can then be affixed to the distal housing, thereby minimizing any adverse affects on the sensitive component that may otherwise result from mounting the first and second components on a single member. In the preferred embodiment, the distal housing includes a cap-shaped head, and the proximal mounting member includes a cylindrical neck section, with the head forming an ablation electrode. In this case, the head can further include a channel for mounting a thermistor therein. The distal catheter assembly can be mounted to the distal end of a catheter tube to form a fully functioning catheter.

RELATED APPLICATIONS

This application is being filed concurrently with application Ser. No.09/903,112, entitled “Distal Catheter Assembly With Proximal MountingMember,” and Ser. No. 09/903,402, entitled “Clamshell Distal CatheterAssembly,” both of which are expressly incorporated herein by reference.

TECHNICAL FIELD

The present invention generally relates to medical devices, and moreparticularly, to methods of assembling catheter tips with sensors.

BACKGROUND OF THE INVENTION

Catheters are widely used in the medical arts. For example, cathetersare sometimes inserted into a patient's body during mapping and ablationprocedures of the patient's heart. Catheters used for such procedurestypically comprise of electrode tips and electrode rings. Various othercomponents may also be incorporated into these medical catheters. Forexample, a steering mechanism allowing the physician to control themovement of the catheter while the catheter is in a patient's body maybe incorporated into the catheter. A thermistor or a thermocouple mayalso be placed at the catheter tip to provide temperature data. Inaddition, such catheters may incorporate other sensors at the tip toassist the physician in performing these delicate procedures.

One type of sensor currently being incorporated into catheter tips is anelectromagnetic sensor, which provides important information to thephysician about the exact location of the catheter tip relative to thepatient's body. An electromagnetic sensor used for such purposes andcommercially available is a “3D” sensor, which employs an orthogonalarrangement of three sensor pairs to provide three-dimensional positioncoordinates of the catheter tip. Details on the structure and use of a“3D” sensor are discussed in PCT publication WO 00/10456, entitled“Intrabody Navigation System for Medical Applications,” which is herebyexpressly and fully incorporated herein by reference.

Incorporating such sensors into catheter tips during assembly can bedifficult. Catheters used in, for example RF ablation and mappingprocedures, tend to be very small in size, thus requiring assemblytechniques that must be precise. In addition, electromagnetic sensorsare highly sensitive to excess thermal energy and magnetic fields. Evenshort exposure to excess thermal energy and magnetic fields may causedamage to these sensors.

Thus, the assembly of distal catheter assemblies that containelectromagnetic sensors are further constrained, since certain heatgenerating steps, for example soldering, may potentially expose thesesensors to excess heat. Further, many of the components incorporatedinto these devices are made from ferrous material, such as stainlesssteel, which can magnetically affect the sensors. Thus, a method forassembling a distal catheter assembly without damaging a magnetic andheat-sensitive component contained therein would be highly desirable.

SUMMARY OF THE INVENTION

The present inventions include distal catheter assemblies, catheters,and methods that minimize damage to sensitive components.

In accordance with a first aspect of the present inventions, a distalcatheter assembly comprises a composite housing that includes a distalmember having a distal cavity formed therein, and a separate proximalmember having a proximal cavity formed therein. By way of non-limitingexample, the composite housing may form a cap-shaped head and acylindrical neck. In this case, the head may form an ablation electrode,and ring electrodes, such as mapping electrodes, may be disposed aroundthe neck. A channel may be formed distal to the cavity, where athermistor can be disposed. The entirety of the cap-shaped head may beformed by the distal member, and the entirety of the cylindrical neckmay be formed by the proximal member. Alternatively, one of thecap-shaped head and cylindrical neck may be formed by both of the distaland proximal members, and the entirety of the other of the cap-shapedhead and cylindrical neck formed by either the distal member or proximalmember.

The distal catheter assembly further comprises a first component, suchas a sensor, mounted within the distal cavity. The distal catheterassembly further comprises a second component mounted on the proximalmember. The second component can be, e.g., a steering assembly, and ifthe housing comprises an ablation electrode, an RF lead. Optionally, ifthe proximal member is hollow, it may include an open window throughwhich the inner surface of the proximal member can be accessed. Forexample, if the second component is soldered to the inner surface of theneck, the open window may provide a working space for the solderingiron. The open window can be formed by, e.g., providing a cutout in theneck.

In accordance with a second aspect of the present inventions, a methodfor assembling a distal catheter assembly comprises providing a distalmember and a proximal member. By way of non-limiting example, the distalmember can form an ablation electrode, in which case, the distal membercan include a channel, where a thermistor can be optionally mountedtherein. The method further comprises mounting a first component, suchas a sensor, within either the distal member or the proximal member by asuitable means, such as potting. The component can be inserted into thedistal member by front-loading it through a proximal opening therein, orcan be inserted into the proximal member by back-loading it through adistal opening therein. The method further comprises mounting anothercomponent, such as a steering assembly or RF wire, on the proximalmember by suitable means, e.g., heat generation, and more specifically,soldering.

The method further comprises affixing the proximal member to the distalmember, e.g., by affixing either the distal end of the proximal memberwithin the proximal end of the distal member or the proximal end of thedistal member within the distal end of the proximal member, e.g., bymeans of bonding or a threaded arrangement. Thus, since the secondcomponent does not come into contact with the proximal member untilafter the first component is mounted thereon, any adverse effects on thefirst component that may otherwise result can be minimized or completelyeliminated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal-sectional view of an exemplary distal catheterassembly constructed in accordance with the present inventions, whereinthe distal catheter assembly is formed of a unibody ablation electrodewith a front-loaded sensor, and a steering assembly and RF wire aremounted thereto using heat generating means.

FIG. 2 is a perspective view of the distal catheter assembly of FIG. 1.

FIG. 2A is a cross-sectional view of the distal catheter assembly ofFIG. 1 taken along the line 2A—2A of FIG. 2.

FIG. 3 is a longitudinal-sectional view of another exemplary distalcatheter assembly constructed in accordance with the present inventions,wherein the distal catheter assembly is formed of a unibody ablationelectrode with a front-loaded sensor, and a steering assembly is mountedthereto using non-heat generating means.

FIG. 3A is a partial perspective view of a steering assembly employed bythe distal catheter assembly of FIG. 3.

FIG. 4A is a side view of an ablation electrode employed by the distalcatheter assembly of FIG. 1, wherein a preferred cutout is particularlyshown.

FIG. 4B is a side view of an ablation electrode employed by the distalcatheter assembly of FIG. 1, wherein an alternatively preferred cutoutis particularly shown.

FIG. 4C is a side view of an ablation electrode employed by the distalcatheter assembly of FIG. 1, wherein still another alternativelypreferred cutout is particularly shown.

FIG. 5A is a perspective view of an open heat sink fixture used to holdthe distal catheter assembly of FIG. 1.

FIG. 5B is a perspective view of the heat sink fixture of FIG. 5A,wherein an ablation electrode is particularly shown mounted therein.

FIG. 5C is a perspective view of the heat sink fixture of FIG. 5B,wherein a sensor is particularly shown mounted within the ablationelectrode.

FIG. 5D is a perspective view of the heat sink fixture of FIG. 5C,wherein a sensor is particularly shown potted within the ablationelectrode.

FIG. 6 is a longitudinal-sectional view of another exemplary distalcatheter assembly constructed in accordance with the present inventions,wherein the distal catheter assembly is formed of a unibody ablationelectrode with a back-loaded sensor.

FIG. 7 is a longitudinal-sectional view of still another exemplarydistal catheter assembly constructed in accordance with the presentinventions, wherein the distal catheter assembly is formed of apreferred two-piece ablation electrode.

FIG. 8 is an exploded side view of the distal catheter assembly of FIG.7, wherein a sensor is being front-loaded into the distal member.

FIG. 9 is an exploded side view of the distal catheter assembly of FIG.7, wherein a sensor is being back-loaded into the proximal member.

FIG. 10 is a longitudinal-sectional view of still another exemplarydistal catheter assembly constructed in accordance with the presentinventions, wherein the distal catheter assembly is formed of analternatively preferred two-member ablation electrode.

FIG. 11 is a longitudinal-sectional view of still another exemplarydistal catheter assembly constructed in accordance with the presentinventions, wherein the distal catheter assembly is formed of apreferred clamshell ablation electrode.

FIG. 12 is an exploded side view of the distal catheter assembly of FIG.11, wherein a pin and hole arrangement is used to align the two membersof the ablation electrode.

FIG. 12A is an exploded side view of the distal catheter assembly ofFIG. 11, wherein a ridge and indentation arrangement is used to alignthe two members of the ablation electrode.

FIG. 13 is a longitudinal-sectional view of still another exemplarydistal catheter assembly constructed in accordance with the presentinventions, wherein the distal catheter assembly is formed of analternatively preferred clamshell ablation electrode.

FIG. 14 is an exploded side view of the distal catheter assembly of FIG.13.

FIG. 15 is a longitudinal-sectional view of still another exemplarydistal catheter assembly constructed in accordance with the presentinventions, wherein the distal catheter assembly is formed of anotheralternatively preferred clamshell ablation electrode.

FIG. 16 is an exploded side view of the distal catheter assembly of FIG.15.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present inventions provide for novel distal catheter assembliescontaining magnetic- and heat-sensitive components, and methods formanufacturing the same. The methods provided are for various distalcatheter assembly designs, including unibody, two-member, and clamshelldistal catheter assemblies. The different assembly techniques used inthe methods provided may include, for example, front- and back-loadingassembly techniques. It is noted that, to the extent that the featuresof the various assemblies and methods described below are similar, theyhave been similarly illustrated and identical reference numbers havebeen used.

Referring to FIGS. 1 and 2, a single-member front-loaded distal catheterassembly 100 comprises a hollow ablation electrode 110 that includes acap-shaped head section 120, a cylindrical neck section 130, and a maincavity 140 formed therein. The head section 120 of the electrode 110forms a rounded semi-enclosed distal tip 170 that includes a narrow openchannel 172 that distally leads to a distal opening 174 and proximallyleads to the cavity 140. The neck section 130 of the electrode 110 formsan open proximal mounting member 150 having a proximal opening 142. Inthe illustrated embodiment, the ablation electrode 110 forms a singlemember unibody design that is composed of a suitably biocompatible, yetelectrically conductive material, such as a 90/10 platinum iridiumalloy.

As illustrated best in FIG. 1, the assembly 100 further comprises athermally and magnetically sensitive sensor 160 and a thermistor 176,which are located in the main cavity 140 and channel 172, respectively.The sensor 160 and thermistor 176 can be suitably affixed within thecavity 140 and channel 172 by, e.g., using a potting material 152, suchas an epoxy or UV adhesive. The sensor 160 and thermistor 176 comprisesensor wires 162 and thermistor wires 164 that extend proximallytherefrom.

The assembly 100 further includes a steering assembly 154 and RF wire156 that are attached, and preferably soldered, to the inside surface ofthe proximal member 150. Potting material 152 is applied to the steeringassembly 154 and RF wire 156 to maintain the structural integrity of thecatheter assembly 100. The steering assembly 154 comprises a resilientcenter support 178 on which two steering wires 180 are soldered orspot-welded. The center support 178 is composed of a flat resilientmaterial, such as stainless steel. The distal end of the center support178 is mounted to the proximal mounting member 150, and the distal endsof the steering wires 180 are suitably mounted on opposite surfaces ofthe center support 178 using a heat generating means, e.g., bysoldering. The proximal ends of these steering wires 180 are connectedto a suitable proximal steering assembly (not shown), the operation ofwhich provides tension to one of the wires 180, thereby bending theassembly 100 in a predetermined direction to provide steering capabilitythereto.

Referring specifically to FIGS. 2 and 2A, the assembly 100 comprises acatheter tube 181, the distal end of which (shown in phantom) isdisposed over the neck section 130 of the electrode 110. The assembly100 further comprises a multitude of mapping ring electrodes 182, whichare suitable mounted around the catheter tube 181 adjacent the necksection 130 of the electrode 110, e.g., by interference fit. Signalwires 183 are suitably mounted to the underside of the mapping ringelectrodes 182 and extend through an opening (not shown) in the cathetertube 181 and proximally out through a catheter lumen (also not shown).To electrically isolate the signal wires 183 from the ablation electrode110, a thin dielectric layer 184, such as polyimide, is disposed betweenthe inner surface of the catheter tube 181 and the outer surface of theneck section 130.

To provide a mounting or soldering area that is located away from thesensor 160, the length of the proximal member 150 is sized to extendproximally from the sensor 160. In this manner, a substantial amount ofheat created by the soldering iron is dissipated before it is conductedto the sensor 160. Also, the length of the proximal member 150 allowsthe steering assembly 154 and RF wire 156, which typically comprisecomponents that are made of a ferromagnetic material, such as stainlesssteel, to be located away from the sensor 160 so as not to magneticallyaffect it.

As can be seen in FIGS. 1 and 2, the assembly 100 comprises a window,and specifically a cutout 158, formed in the neck section 130 of theelectrode 110. This provides a multitude of advantages to themanufacturing process. For example, the cutout 158 provides theassembler with a better view of the solder location, which wouldotherwise be difficult, if not impossible, to view. Also, the cutout 158provides more space to locate the soldering iron on the solder area,which would otherwise be difficult to do, given the limited space withinthe neck section 130 of the electrode 110. In addition, the cutout 158provides the assembler with space to move the sensor and thermistorleads 162 and 164 away from the solder area, allowing more space duringthe soldering process.

Referring to FIGS. 4A-4C, various types of cutouts 158 can be formed inthe neck section 130 for improved ease of mounting the steering assembly154 and RF wire 156 on the assembly 100. Specifically, a neck section130(1) illustrated in FIG. 4A comprises a 90-degree stepped cutout158(1). The height of the neck section 130(1) adjacent to the cutout158(1) can be any value, giving due consideration to the relationshipbetween the height and the structural rigidity of the neck section130(1), i.e., as the height decreases, the structural rigidity of theneck section 130(1) decreases. The neck section 130(2) illustrated inFIG. 4B comprises an arcuate cutout 158(2). The geometry of the arcuatecutout 158(2) should be selected to maintain the structural rigidity ofthe neck section 130(2). The neck section 130(3) illustrated in FIG. 4Ccomprises a tapered cutout 158(3). In each of the neck sections 130illustrated in FIGS. 4A-4C, the cutouts 158 are formed to expose aninner surface of the neck section 130 to facilitate the manufacturingprocess. It should be noted that cutouts that do not have sharp corners,such as the cutouts 158(2) and 158(3) illustrated in FIGS. 4B and 4C aremore preferable than cutouts that do have sharp corners, such as thecutout 158(1) illustrated in FIG. 4A, since sharp corners typicallycause stress points that are more prone to fracture when subjected tostress.

Having now described the structure of the catheter assembly 100, we nowdescribe a method assembling it. First, the sensor 160 and thermistor176 are potted within the respective cavity 140 and a channel 172 of theablation electrode 110 using the potting material 152. The thermistor176 is located within the channel 172 by front-loading it through theproximal opening 172 of the neck section 130, and then the sensor 160 islocated within the cavity 140 by front-loading it through the proximalopening 142 of the neck section 130. Alternatively, the thermistor 176can be located within the channel 172 by back-loading it through thedistal opening 174 of the head section 120 prior or subsequent to theloading of the sensor 160.

Once the sensor 160 and thermistor 176 are installed within theelectrode 110, a heat sink fixture 800 (shown in FIGS. 5A-5D) can beused to provide a stable hold on the assembly 100, as well as tofacilitate the dissipation of heat during the soldering process. The useof the heat sink fixture 800 is especially important in assembling theassembly 100, because the soldering of RF wires 156 and steeringassembly 154 generally occurs after the sensor 160 has already beenincorporated into the assembly 100. Thus, to protect the sensor 160 fromheat damage, the assembly 100 should preferably be placed in the fixture800 prior to any soldering operations.

As illustrated in FIG. 5A, the fixture 800 includes three sleeve arms810, which are composed of a thermally conductive material, for example,a beryllium copper alloy. The fixture 800 can be operated to close thesleeve arms 810, e.g., by pneumatic means. To this end, the head section120 of the electrode 110 is temporarily mounted within the arms 810 ofthe heat sink fixture 800, and the sensor and thermistor wires 162 and164 are then carefully pulled out through the proximal opening 142 (FIG.5B). The RF wire 156 and steering assembly 154 are then soldered to theinside surface of the proximal mounting member 150 (FIG. 5C). Aspreviously described above, the positional relationship between theproximal mounting member 150 and the sensor 160 is such that the thermalenergy generated by the soldering process and any magnetic fieldproduced by the steering assembly 154 and RF wire 156 substantiallydissipates before it reaches the sensor 160. The heat sink fixture 800further facilitates the dissipation of heat away from the head section120 of the electrode 110, and thus away from the sensor 160.

Next, the portion of the cavity 140 proximal to the sensor 160 is pottedwith the potting material 152 to maintain the structural integrity ofthe assembly 100 (FIG. 5D). Lastly, the dielectric layer 184 is disposedaround the outer surface of the neck section 130, and the catheter tube181 and ring electrodes 182 are interference fit around the dielectriclayer 184, providing a secure and electrically isolated mount to theablation electrode 110.

Referring to FIG. 3, a single-member front-loaded distal catheterassembly 190 is similar to the afore-described catheter assembly 100,with the exception that the steering assembly 154 is not mounted to theproximal member using heat generating means, but rather is mountedthereto using non-heat generating means.

Specifically, the catheter assembly 190 comprises an ablation electrode192 that includes a proximal member 194 to which the steering assembly154 and RF wire 156 are mounted. The RF wire 156 is soldered to theinside or outside of an edge 193 of the proximal member 194. As will bedescribed below, this and the low profile of the RF wire allows enoughspace for the sensor 160 to be front-loaded into the main cavity 140.Like with the catheter assembly 100, the distal ends of the steeringwires 180 are suitably mounted on opposite surfaces of the centersupport 178, e.g., by soldering or spot-welding, to form the steeringassembly 154. Unlike with the catheter assembly 100, however, thesteering assembly 154 is not soldered to, but is merely potted withinthe proximal mounting member 194 using potting material 152.

To improve the adhesion of the steering assembly 154 to the proximalmounting member 194, the inside surface of the proximal mounting member194 is preferably roughened prior to potting the steering assembly 154thereto. Additionally, as can be seen in FIG. 3A, the distal ends of thesteering wires 180 are curled or kinked away in a plane perpendicular tothe surface of the center support 178 to provide a more reliablemechanical hold between the steering assembly 154 and the pottingmaterial 152. Alternatively, the steering wires 180 may be curled orkinked in a plane parallel to the surface of the center support 178. Ascan be seen in FIG. 3, the proximal member 194 does not include acutout, since the RF wire is soldered to the edge 193 of the proximalmember 194, and minimal space is required to pot the steering assembly154 within the proximal member 194.

The method of assembling the catheter assembly 190 is similar to that ofthe catheter assembly 100 with the exception that the RF wire 156 issoldered to the proximal member 194 prior to front-loading the sensor160 and thermistor 176 into the main cavity 140, and the steeringassembly 154 is mounted to the proximal member 194 using non-heatgenerating means. Thus, the heat sink fixture 800, although stillpreferably used for convenience of manufacture, need not be used todissipate the heat away from the sensor 160.

Referring to FIG. 6, a back-loaded distal catheter assembly 200 isillustrated. The assembly 200 is similar to the afore-described assembly100, with the exception that it includes an electrode 202 that providesfor back-loading of the sensor 160 therein. To this end, a head section204 of the electrode 202 includes a distal opening 208 that is largeenough to allow the sensor 160 to be inserted within a main cavity 206formed within the electrode 202. The assembly 200 further includes aplug 210 that is snugly fit within the distal opening 208, e.g., in athreaded arrangement. The plug 210 has a narrow channel 212, whichhouses the thermistor 176. Alternatively, use of the plug 210 can beforegone if the sensor 160 and corresponding distal opening 208 aresmall enough.

The method of assembling the assembly 200 is generally the same as themethod of assembling the assembly 100, with the exception that thesensor 160 is back-loaded into the main cavity 140 of the electrode 202after the steering assembly 154 and RF wire 156 are soldered to theproximal mounting member 150. After the sensor 160 is mounted within themain cavity 140, the plug 210 is installed within the distal opening 208to partially seal the main cavity 140. Thus, this back-loading procedureeliminates the risk of exposure of the sensor 160 to heat generated bythe soldering process. Further, under this approach, the use of thepreviously described heat sink fixture 800, although preferably used forease of manufacture, may be foregone, since heat generated by thesoldering process dissipates prior to mounting the sensor 140.

Referring to FIG. 7, a two-piece distal catheter assembly 300 isillustrated. The assembly 300 is similar to the afore-described assembly100, with the exception that it comprises an ablation electrode 302formed by two separate axially aligned distal and proximal members 304and 306, respectively. In particular, the distal member 304 forms acap-shaped head 308, and the proximal member 306 forms acylindrically-shaped neck 310. The distal member 304 includes a distalcavity 312, and the proximal member 306 includes a proximal cavity 314,which together form a main cavity 320 when the distal and proximalmembers 304 and 306 are mated together, e.g., in a threaded arrangementor bonded together using silver epoxy. The distal member 304 furthercomprises a distal channel 316, and the proximal member 306 comprises adistal opening 318. The sensor 160 is mounted within the main cavity320, and the thermistor 176 is disposed in the distal channel 316. Asillustrated, the distal and proximal members 304 and 306 can becharacterized as respective female and male members, with the distal endof the proximal member 306 fitting snugly within the proximal end of thedistal member 304. As will be described in further detail below, thisarrangement allows the sensor 160 and thermistor 176 to be fully mountedwithin the ablation electrode 302, well after the soldering processtakes place.

The method of assembling the assembly 300 is generally the same as themethod of assembling the assembly 100, with the exception that theinternal components of the assembly 300, for example the sensor 160, thethermistor 176, the steering assembly 154 and the RF wire 156 aremounted when the distal and proximal members 304 are 306 are stillseparate. For example, the sensor 160 and thermistor 176 can berespectively mounted within the distal cavity 312 and the distal channel316 of the distal member 304, using potting material 152, and thesteering assembly 154 and RF wire 156 can be soldered within theproximal cavity 314 of the proximal member 306 when the distal andproximal members 304 and 306 are separate, as illustrated in FIG. 8.Alternatively, the steering assembly 154 and RF wire 156 can be solderedwithin the proximal cavity 314 of the proximal member 306, and then thesensor 160 can be back-loaded into the same proximal cavity 314 via thedistal opening 318, as illustrated in FIG. 9. The steering assembly 154,RF wire 156, and sensor 160 are then potted with the potting material152.

In any event, after mounting the internal components, i.e., the sensor160, thermistor 176, steering assembly 154, and RF wire 156, theproximal and distal members 304 and 306 are then fitted together (in adirection indicated by arrows 322) to form the integral ablationelectrode 302 and main cavity 320. Then the entire main cavity 320 ispotted with the potting material 152. Thus, the sensor 160 does not comeinto contact with the proximal member 306 until well after the solderingprocess has taken place, thereby eliminating the risk that heatgenerated by the soldering process is transferred to the sensor 160.This method also allows cleaning of the solder area, and prevents thesensor and thermistor wires 162 and 164 from hindering the solderingprocess.

Referring to FIG. 10, another two-piece distal catheter assembly 400 isillustrated. The assembly 400 differs from the afore-described assembly300 in that the head of the ablation electrode is formed of two pieces.In particular, the assembly 400 comprises an ablation electrode 402 thatincludes a distal member 404 that forms only the distal end 412 of acap-shaped head 408, and a proximal member 406 that forms the proximalend 414 of the head 408 and the entirety of a cylindrically-shaped neck410. Like the assembly 300, the distal member 404 includes a distalcavity 416 and distal channel 418, and the proximal member 406 includesa proximal cavity 420, which together form a main cavity 422 when thedistal and proximal members 404 and 406 are mated together, e.g., in athreaded arrangement or bonded together using silver epoxy.

As illustrated, the distal and proximal members 404 and 406 can becharacterized as respective male and female members, with the proximalend of the distal member 404 fitting snugly within the distal end of theproximal member 406. Like the assembly 300, this arrangement allows thesensor 160 to be fully mounted within the ablation electrode 402 wellafter the soldering process takes place. The method of assembling theassembly 400 is similar to the method of assembling the assembly 300 inthat, prior to affixing the distal and proximal members 404 and 406together, the steering assembly 154 and RF wire 156 are mounted withinthe proximal cavity 420 of the proximal member 406 and the sensor 160 iseither mounted within the distal cavity 416 of the distal member 404(similarly to the assembly 300 shown in FIG. 8), or back-loaded into theproximal cavity 420 of the proximal member 406 (similar to the assembly300 shown in FIG. 9). In any event, the advantages described withrespect to the assembly 300 are achieved.

Referring to FIG. 11, a clamshell distal catheter assembly 500 isillustrated. The assembly 500 is similar to the afore-described assembly100, with the exception that it is formed of two clamshell members. Inparticular, the assembly 500 comprises an ablation electrode 502 formedby complementary bottom and top lateral housing sections 504 and 506,respectively, which for purposes of this specification, are housingsections whose lateral sides fit together in a complementary fashion toform a composite housing. It should be noted that the terms “top” and“bottom” are used for purposes of illustration, and it should beunderstood that the use of such terms when identifying certain featureson an actual distal catheter assembly will change with the particularorientation of the distal catheter assembly.

The bottom housing section 504 comprises a bottom head section 508 andbottom neck section 510, and the top housing section 506 comprises a tophead section 512 and top neck section 514, which when affixed to eachother using an electrically conductive bonding material, such as silverepoxy, forms a cap-shaped head 516 and cylindrically-shaped neck 518having a main cavity 520 and distal channel 522 formed therein. As canbe seen, the sensor 160 and thermistor 176 are respectively mountedwithin the main cavity 520 and distal channel 522. Alignment of thehousing sections 504 and 506 is accomplished by a pin and holearrangement. Specifically, the bottom housing section 504 includes apair of pinholes 524, and the top housing section 506 includes a pair ofcomplementary pins 526 that fit together to align the respective housingsections 504 and 506 (shown in FIG. 12). As will be described in furtherdetail below, this arrangement allows the sensor 160 and thermistor 176to be fully mounted within the ablation electrode 502, well after thesoldering process takes place. Alternatively, as illustrated in FIG.12A, either the bottom housing section 504 can have one or more ridges525, and the top housing section 506 can have one or more complementaryindentations 527 that engage the ridges 525 to provide alignment betweenthe respective sections 504 and 506.

Referring to FIG. 12, the assembly 500 is assembled by first solderingthe steering assembly 154 and RF wire 156 to the bottom neck section510. After the heat generated by the soldering process has dissipatedfrom the bottom housing section 504, the sensor 160 and thermistor 176are then mounted within the bottom head section 508, e.g., by pottingwith an epoxy. Alternatively, the sensor 160 and thermistor 176 can besimilarly mounted within the top head section 512. In any event, afterthe internal components are mounted, the housing sections 504 and 506are affixed to each other, with the pair of complementary pinholes 524and pins 526 being in engagement with each other for purposes ofalignment.

Referring to FIG. 13, another clamshell distal catheter assembly 600 isillustrated. The assembly 600 is similar to the afore-described assembly500, with the exception that only the neck is formed of two clamshellmembers. In particular, the assembly 600 comprises an ablation electrode602 formed by bottom and top complementary lateral housing sections 604and 606, respectively. The bottom housing section 604 comprises acap-shaped head 608 and a bottom neck section 610, and the top housingsection 606 only comprises a top neck section 612. When the housingsections 604 and 606 are affixed to each other using an electricallyconductive bonding material, such as silver epoxy, acylindrically-shaped neck 614, along with the head 608, is formed, withthe sensor 160 and the thermistor 176 being respectively mounted withina main cavity 616 and distal channel 618. To facilitate the mounting ofthe sensor 160 and thermistor 176, a proximal opening 620 and distalopening (not shown) are provided in the head 608. Again, alignment ofthe housing sections 604 and 606 is accomplished by a pin and hole orridge and indentation arrangement.

Referring to FIG. 14, the assembly 600 is assembled by first solderingthe steering assembly 154 and RF wire 156 to the bottom neck section610. Alternatively, the steering assembly 154 and RF wire 156 can besimilarly mounted within the top neck section 612. After the heatgenerated by the soldering process has dissipated from the bottomhousing section 604, the sensor 160 and thermistor 176 are then mountedwithin the head 608, e.g., by potting with an epoxy. In the illustratedembodiment, the sensor 160 is front-loaded into the head 608 through theproximal opening 620, and the thermistor 176 is back-loaded into thehead 608 through the distal opening (not shown). The absence of the tophousing section 606 allows suitable clearance for front-loading of thesensor 160 through the proximal opening 620. After the internalcomponents are mounted, the bottom and top housing sections 604 and 606are affixed to each other.

Referring to FIG. 15, still another clamshell distal catheter assembly700 is illustrated. The assembly 700 is similar to the afore-describedassembly 500, with the exception that the neck and only a portion of thehead is formed of two clamshell members. In particular, the assembly 700comprises an ablation electrode 702 formed by bottom and topcomplementary lateral housing sections 704 and 706, respectively. Thebottom housing section 704 comprises a bottom head section 708 and abottom neck section 710, and the top housing section 706 also comprisesa top head section 712 and a top neck section 714. When the housingsections 704 and 706 are affixed to each other using an electricallyconductive bonding material, such as silver epoxy, a cap-shaped head 716and cylindrically-shaped neck 718 are formed, with the sensor 160 andthermistor 176 being respectively mounted within a main cavity 720 anddistal channel 722. As can be seen, only the proximal end of the head716 is formed by mounting of the housing sections 704 and 706. Tofacilitate the mounting of the sensor 160 and thermistor 176, a proximalopening 724 (illustrated in FIG. 16) and distal opening (not shown) areprovided in the head 716. Again, alignment of the housing sections 704and 706 is accomplished by a pin and hole arrangement or a ridge andindentation arrangement.

Referring to FIG. 16, the assembly 700 is assembled by first solderingthe steering assembly 154 and RF wire 156 to the bottom neck section710. Alternatively, the steering assembly 154 and RF wire 156 can besimilarly mounted within the top neck section 714. After the heatgenerated by the soldering process has dissipated from the bottomhousing section 704, the sensor 160 and thermistor 176 are then mountedwithin the bottom head section 708, e.g., by potting with an epoxy. Inthe illustrated embodiment, the sensor 160 is front-loaded into thebottom head section 708 through the proximal opening 724, and thethermistor 176 is back-loaded into the bottom head section 708 throughthe distal opening (not shown). The absence of the top housing section706 allows suitable clearance for front-loading of the sensor 160through the proximal opening 724. After the internal components aremounted, the housing sections 704 and 706 are affixed to each other.

Although particular embodiments of the present invention have been shownand described, it will be understood that it is not intended to limitthe invention to the preferred embodiments and it will be obvious tothose skilled in the art that various changes and modifications may bemade without departing from the spirit and scope of the presentinvention. Thus, the invention is intended to cover alternatives,modifications, and equivalents, which may be included within the spiritand scope of the invention as defined by the claims.

All publications, patents, and patent applications cited herein arehereby incorporated by reference in their entirety for all purposes.

What is claimed is:
 1. A method for assembling a distal catheterassembly, comprising: providing a distal member and a proximal member;mounting a first catheter component within said distal member, saidfirst component being adversely affected in the presence of anenvironmental condition; mounting a second catheter component, on saidproximal member, said mounting of said second component creating saidadverse environmental condition; and affixing said proximal member tosaid distal member subsequent to said mounting of said first and secondcomponents to form a composite electrode.
 2. The method of claim 1,wherein said electrode is an ablation electrode.
 3. The method of claim1, wherein said environmental condition is excess thermal energy.
 4. Themethod of claim 1, wherein said environmental condition is excessmagnetic energy.
 5. The method of claim 1, wherein said first componentcomprises a magnetic sensor.
 6. The method of claim 1, wherein saidsecond component comprises a steering assembly.
 7. The method of claim1, wherein said second component comprises an RF lead.
 8. The method ofclaim 1, wherein said second component is mounted on said proximalmember by means of heat generation.
 9. The method of claim 1, whereinsaid composite electrode is a tip electrode.
 10. The method of claim 9,wherein said distal member forms a cap-shaped head.
 11. A method forassembling a distal catheter assembly, comprising: providing a distalmember and a proximal member; mounting a first catheter component withinsaid distal member; mounting a second catheter component on saidproximal member; and screwing said proximal member to said distal membersubsequent to said mounting of said first and second components.
 12. Themethod of claim 11, wherein said distal member and said proximal memberare screwed together to form a composite electrode.
 13. The method ofclaim 12, wherein said composite electrode is a tip electrode.
 14. Themethod of claim 13, wherein said distal member forms a cap-shaped head.15. The method of claim 11, wherein said first component is adverselyaffected in the presence of an environmental condition, and saidmounting of said second component creates said environmental condition.16. The method of claim 11, wherein said environmental condition isexcess thermal energy.
 17. The method of claim 11, wherein saidenvironmental condition is excess magnetic energy.
 18. The method of 11,wherein said first component comprises a magnetic sensor.
 19. The methodof claim 11, wherein said second component comprises one or both of asteering assembly and an RF lead.
 20. The method of claim 11, whereinsaid second component is mounted on said proximal member by means ofheat generation.
 21. A method for assembling a distal catheter assembly,comprising: providing a distal member and a proximal member; mounting asecond catheter component on said proximal member; mounting a firstcatheter component into said proximal member through a distal opening ofsaid proximal member subsequent to said mounting of said second cathetercomponent; and affixing said proximal member to said distal membersubsequent to said mounting of said first and second components, whereinat least a portion of said first catheter component is disposed withinsaid distal member.
 22. The method of claim 21, wherein said distalmember and said proximal member are affixed together to form a compositeelectrode.
 23. The method of claim 22, wherein said composite electrodeis a tip electrode.
 24. The method of claim 23, wherein said distalmember forms a cap-shaped head.
 25. The method of claim 21, wherein saidfirst component is adversely affected in the presence of anenvironmental condition, and said mounting of said second componentcreates said environmental condition.
 26. The method of claim 25,wherein said environmental condition is excess thermal energy.
 27. Themethod of claim 25, wherein said environmental condition is excessmagnetic energy.
 28. The method of claim 25, wherein said firstcomponent comprises a magnetic sensor.
 29. The method of claim 25,wherein said second component comprises one or both of a steeringassembly and an RF lead.
 30. The method of claim 25, wherein said secondcomponent is mounted on said proximal member by means of heatgeneration.